Otto Selz (14 February 1881 – 27 August 1943) was a Germanpsychologist from Munich, Bavaria, who formulated the first nonassociationist theory of thinking, in 1913.[1][2] Selz used the method of introspection, but unlike his predecessors, his theory developed without the use of images and associations. Wilhelm Wundt used the method of introspection in the 1880s, but thought that higher-level mental processes could not be studied in the scientific laboratory.

Selz's ideas anticipated some major concepts in modern cognitive psychology, including the following:

The unit of thought is the directed association.

Understanding a problem involves forming a structure.

Solving a problem involves testing for conditions.

Selz's career was shortened by Nazi policies in Europe, which banned him from his profession and eventually took his life, in the Auschwitz concentration camp. Until recently, his works were largely untranslated from German into English.

In 2004, philosopher and psychologist Michel ter Hark (Groningen, the Netherlands) published a book called Popper, Otto Selz and the Rise of Evolutionary Epistemology, in which he claims that Karl Popper got part of his ideas from Selz. Selz himself never published his ideas, partly because of the rise of Nazism which forced him to quit his work in 1933, and the prohibition of referencing to Selz' work.